New best 60' with my 8 3/4

Posted By: dragram440

New best 60' with my 8 3/4 - 07/07/14 10:21 PM

I went racing all last weekend and just cant get over how good the 60' times are for the setup. It ran 1.47 for the best and seems to just be working. The car has the stock type springs and used Rancho shocks that I just bought off of here and cheep monroe shocks up front, Pinion snubber. I leave off of a idle with the foot brake. The 8 3/4 has around 120 passes on it so I think I will open it up and check it out just to make sure everything is still good. I was also thinking maybe I should put the Mark Williams cap on it. Think the cap is worth it? I was maybe thinking of trying to add some more power.

Posted By: Bad340fish

Re: New best 60' with my 8 3/4 - 07/07/14 10:32 PM

I am sure you will find that everything looks fine up until it doesn't.

Posted By: MR_P_BODY

Re: New best 60' with my 8 3/4 - 07/07/14 10:46 PM

The cap does help... but the pinion flex is what will
kill it... on a heavy car you have greater friction on
the tire and that causes more flex.. I've been running
my alum center for about 9 years now(racing, not the time
I've let the car sit).. it has some nice stuff in it
but my car is light and its less apt to break this ..
I had 600+ passes on my stock 8 3/4 with just a back brace
till it spit the caps off(the caps went first but still
due to flex on the pinion)

Posted By: Quicktree

Re: New best 60' with my 8 3/4 - 07/07/14 11:17 PM

i wouldn't worry, 8-3/4s are bullet proof

Posted By: dragram440

Re: New best 60' with my 8 3/4 - 07/07/14 11:20 PM

Bullet proof? I would like to know what is bulletproof? Anyone on here ever break a dana 60 or a 9"? They all break at some point!

Posted By: TheOtherDodge

Re: New best 60' with my 8 3/4 - 07/07/14 11:23 PM

I ran and broke 2 8 3/4 rears before I switched to a Dana. I never broke one in my Challenger (low 9's or in my current truck) which both weighed 3400 lbs.

Posted By: justinp61

Re: New best 60' with my 8 3/4 - 07/07/14 11:23 PM

Quote:

Bullet proof? I would like to know what is bulletproof? Anyone on here ever break a dana 60 or a 9"? They all break at some point!

Noooooooooooo..........9" rears never break.

BTW I went 1.38 one time with my 8 3/4.

Posted By: Thumperdart

Re: New best 60' with my 8 3/4 - 07/07/14 11:39 PM

Quote:

Quote:

Bullet proof? I would like to know what is bulletproof? Anyone on here ever break a dana 60 or a 9"? They all break at some point!

Noooooooooooo..........9" rears never break. BTW I went 1.38 one time with my 8 3/4.

Gotcha beat.............went two 1.36`s and 6.22`s back to back but I don`t race much.........

Posted By: racerx

Re: New best 60' with my 8 3/4 - 07/07/14 11:59 PM

Quote:

Quote:

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Bullet proof? I would like to know what is bulletproof? Anyone on here ever break a dana 60 or a 9"? They all break at some point!

Noooooooooooo..........9" rears never break. BTW I went 1.38 one time with my 8 3/4.

Gotcha beat.............went two 1.36`s and 6.22`s back to back but I don`t race much.........

1 more I went 1.28's on my 8 3/4

Posted By: Thumperdart

Re: New best 60' with my 8 3/4 - 07/08/14 12:02 AM

Quote:

Quote:

Quote:

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Bullet proof? I would like to know what is bulletproof? Anyone on here ever break a dana 60 or a 9"? They all break at some point!

Noooooooooooo..........9" rears never break. BTW I went 1.38 one time with my 8 3/4.

Gotcha beat.............went two 1.36`s and 6.22`s back to back but I don`t race much.........

1 more I went 1.28's on my 8 3/4

So much for that.............

Posted By: joedust451

Re: New best 60' with my 8 3/4 - 07/08/14 09:40 AM

I made at least 250 1.50-1.56 with stock axles at 3100 lbs. in my 8.3/4.

Just last year i drove my 78 cutlass to the track a few times & pulled off 1.72-1.73 60fts. with a worn out 7.5" rearend on big MT DRs.

, It howled all the way there & back home, 110 mile round trip, the car weighs about 3400 lbs.

Posted By: MR_P_BODY

Re: New best 60' with my 8 3/4 - 07/08/14 11:49 AM

Quote:

Quote:

Quote:

Quote:

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Bullet proof? I would like to know what is bulletproof? Anyone on here ever break a dana 60 or a 9"? They all break at some point!

Noooooooooooo..........9" rears never break. BTW I went 1.38 one time with my 8 3/4.

Gotcha beat.............went two 1.36`s and 6.22`s back to back but I don`t race much.........

1 more I went 1.28's on my 8 3/4

So much for that.............

I have a bunch of 1.19s on my 8 3/4.. I had a ton of
1.24s - 1.25s on the stock 8 3/4 with just a back brace

Posted By: Quicktree

Re: New best 60' with my 8 3/4 - 07/08/14 12:19 PM

I have a 1.0 with a 9"

Posted By: racerx

Re: New best 60' with my 8 3/4 - 07/08/14 02:00 PM

Show off....Lol

Posted By: Copper Dart

Re: New best 60' with my 8 3/4 - 07/08/14 03:13 PM

I have a 6......, does that count?

Posted By: 340B5

Re: New best 60' with my 8 3/4 - 07/08/14 04:53 PM

http://www.moparts.org/Tech/Archive/axle/pic/rrdd02.jpg

All I'm going to say. 742 is second from left.

Posted By: Sport440

Re: New best 60' with my 8 3/4 - 07/08/14 10:07 PM

I dont know what your car weighs, but Im sure its no liteweight. At best 3200 or so??

With your ET and 493, I think I would skip on the expense of the MW cap and the Machining that goes along with that and step up to a better rear axle.

Apply the finances in a different direction IMO, Especially if your going to be adding some power to a already strong combo.

Posted By: dragram440

Re: New best 60' with my 8 3/4 - 07/08/14 10:14 PM

Quote:

Quote:

Quote:

Bullet proof? I would like to know what is bulletproof? Anyone on here ever break a dana 60 or a 9"? They all break at some point!

Noooooooooooo..........9" rears never break. BTW I went 1.38 one time with my 8 3/4.

Gotcha beat.............went two 1.36`s and 6.22`s back to back but I don`t race much.........

3800 lbs ?

Posted By: Thumperdart

Re: New best 60' with my 8 3/4 - 07/08/14 10:18 PM

Quote:

Quote:

Quote:

Quote:

Bullet proof? I would like to know what is bulletproof? Anyone on here ever break a dana 60 or a 9"? They all break at some point!

Noooooooooooo..........9" rears never break. BTW I went 1.38 one time with my 8 3/4.

Gotcha beat.............went two 1.36`s and 6.22`s back to back but I don`t race much.........

3800 lbs ?

No sir, not at that weight I was more less joking about the 60`s. Your car flys man...........

Posted By: dragram440

Re: New best 60' with my 8 3/4 - 07/08/14 10:28 PM

My car certainly does not fly. I finally won my first round in eliminations last weekend, only took 3 1/2 years. I do have 35 spline axles, spool, back brace, and with 3.91 gears I get a good contact patch from the ring to the pinion. I do have a 742 carrier. Are there any benifits from carrier to carrier?

Posted By: Sport440

Re: New best 60' with my 8 3/4 - 07/08/14 11:03 PM

I was going to ask if it was back braced. I figured it was. That 3.91 gear helps that rear survive IMO.

With a 4.56 gear it would probably blow your first time out with your ET and 3800#

Was wondering what stall vert you had too. You can get a 1.5+ Flash torque multiplication.

Example on the possible differences between the two.

Say you have 600# of torque at stall with the motor. Say your verts good for a 1.5 flash multiplication, thats 900#

900# x 2.45 x 3.91 = 8621# at the pinion.

900# x 2.45 x 4.56 = 10054# at the pinion.

I bet both those numbers divided by two may come close to exceeding your current 35 spline axles rating limits. Like I stated, that 3.91 is helping things.

Posted By: dragram440

Re: New best 60' with my 8 3/4 - 07/08/14 11:06 PM

The converter is a 8" coan, It flashes to about 5000 maybe 5100.

Posted By: Tig

Re: New best 60' with my 8 3/4 - 07/09/14 12:59 AM

I recently bust a Dana

Posted By: Thumperdart

Re: New best 60' with my 8 3/4 - 07/09/14 02:39 AM

Quote:

My car certainly does not fly. I finally won my first round in eliminations last weekend, only took 3 1/2 years. I do have 35 spline axles, spool, back brace, and with 3.91 gears I get a good contact patch from the ring to the pinion. I do have a 742 carrier. Are there any benifits from carrier to carrier?

Runs hard at that weight.............

Apparently the 742 is the one to have from what I`ve heard and mines 9-10 years goin strong.

Posted By: CraigS

Re: New best 60' with my 8 3/4 - 07/09/14 04:15 AM

My car 60's at 1.46-1.48 440.3280lbs Broke the 8 3/4 6 times before I finally bought the dana.I had the 8 3/4 backbraced,mark Williams caps moser axles(35 spline) and spool, Billet yoke...completely maxed out but still breaks.This is an ongoing conversation on here,but my experience is to buy the dana after the first time you break your 8 3/4.

Posted By: Bad340fish

Re: New best 60' with my 8 3/4 - 07/09/14 01:59 PM

Quote:

I recently bust a Dana

Looks like the ring gear only failed because the carrier did.

Posted By: 1967dartgt

Re: New best 60' with my 8 3/4 - 07/09/14 02:16 PM

Was just out last weekend with a friend and a 8 3/4 it went 1.25 with 4.56 gears at 2900+ lbs.

Posted By: justinp61

Re: New best 60' with my 8 3/4 - 07/09/14 03:19 PM

Quote:

my experience is to buy the dana after the first time you break your 8 3/4.

That's what I did. I went 1.38 one time, the second attempt it shucked several teeth off the ring gear. 742, 4.30 Richmond gear, less than 60 passes behind my 340 going 1.54-56 60' and maybe 1500 street miles. The Dart weighed 3240 at the time.

Posted By: FlyFish

Re: New best 60' with my 8 3/4 - 07/09/14 04:41 PM

I'm not sure what I did right, but I have been running the same 8 3/4 carrier with 4.10 gears, Moser 35 spline axles and a spool for 13 years. I bent the stock housing 2 years ago after adding Caltracs (crushed the axle tube), so I replaced it with a Moser fabricated housing with a back brace (the MO875)....still going strong. Not sure on the weight of my car because I have not weighed it in over 10 years, but it is between 3250 and 3200 lbs, foot-braked, 1.45-1.50 60' times, mid 10's in the 1/4.

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